The invention relates to generally to windshield wiper having a wiper arm that is driven via a drive shaft and has a fastening element, a hinge element pivotally connected to the fastening element with a swivel joint, a wiper rod on which a wiper blade is pivotally connected, and a spray nozzle.
Known windshield wipers have a wiper arm, which is made up of a fastening element and a hinge element, which is pivotably connected to it via a swivel joint and has a wiper rod. A hooklike end of the wiper rod engages a suspension box of a wiper blade, which is formed by two side cheeks of a middle bracket and includes a hinge bolt. The hinge thus formed guides the wiper blade over the vehicle window during the swiveling motion. The wiper blade has what is as a rule a multi-member support bracket system, with subordinate brackets pivotably connected to the middle bracket, at least some of which subordinate brackets, with claws on their ends, retain a wiper strip by its head strip. The multi-member support bracket system and spring rails placed in the head strip make it possible during wiping for the wiper strip to adapt, with a uniform contact pressure, to a curved windshield. To that end, a tension spring prestresses the swivel joint. The wiper arm is secured with its fastening element on a drive shaft and is driven by it in the wiping motion.
Such windshield wipers are known, for instance from German Patent Disclosure DE 37 44 237 A1. In simple versions, subordinate brackets, also known as intermediate brackets and claw brackets, can be dispensed with. In the simplest case, the middle bracket itself has claws, with which it retains the wiper strip.
Windshield washing systems for vehicles are as a rule used in conjunction with windshield wipers. They are actuated if the moisture from precipitation does not suffice to clean the vehicle window. They include a water container, spray nozzles, and a pump which pumps water, sometimes admixed with cleaning and antifreeze agents, under pressure out of the water container to the spray nozzles. As a rule, the spray nozzles are secured to some part of a vehicle body, such as a hood, window frame, or the like. To prevent the spray nozzles from freezing at temperatures below the freezing point, heating elements are integrated into the spray nozzles and communicate with a power supply via plugs located on the outside. The heating elements require relatively great effort and expense for producing the spray nozzles and great effort and expense for assembly for laying the electric lines and contacting the plugs.
It is already known for spray nozzles to be secured as additional components to the wiper blade and thus for the spray water to be distributed over the wiping region directly with a short length of stream. Since the spray water is concentrated on a region in the vicinity of the wiper blade and is washed off again within the shortest possible time by the wiping motion, the view is hindered only briefly by the spray water applied. One disadvantage of such systems is that the effects of weather, especially hail and strong sunshine, greatly affect the flexible parts of this arrangement, which are needed for spanning the hinged regions between the wiper arm and the wiper blade. Furthermore, the spray nozzles and water lines, which are exposed to the relative wind, rapidly freeze closed at temperatures below the freezing points, unless antifreeze is admixed with the water. Frozen water lines and spray nozzles can be defrosted again as a rule only with great effort.
In an earlier German Patent Application, DE 198 15 171.3, a wiper arm is described on the hinge part of which, or a wiper rod integrally connected to the hinge part, spray nozzles are disposed. The spray nozzles are located in a nozzle body, which is accommodated in a bulge of the hinge part that has an injection opening for the spray stream, or is clipped, protruding downward, in a lateral mount on the wiper rod. It is also possible for two nozzle bodies to be provided, which are joined to one another by means of a rigid or flexible connecting piece. The nozzle bodies are easily replaced and are well protected from environmental factors.
A heating device, passed in the form of a wire through a water supply line and embodied as a heating coil in the nozzle body, is integrated into windshield wiper system. The heating device fits only one type of windshield wipers, so that a large number of different heating devices have to be kept on hand. Furthermore, simple solutions are obtained by providing that the nozzle bodies are integrally joined together and are produced from plastic as an injection-molded part. By means of the nozzle bodies distributed along the wiper arm, the spray water is well distributed over the wiping region, especially if a spray stream is directed into a lower region directly in front of the wiper blade. Since this arrangement results in short stream lengths, the relative wind can have only little effect on spray water distribution, even at a relatively high vehicle speed.
According to the invention, an electric resistance heating line in wire form is guided through the water line to the spray nozzles and has two insulated, current-carrying leads. The leads are connected on one end to an electric power supply, while on their other end they are connected to one another and together with the spray nozzle, which is made from a heat-conducting material, form a contact point with good heat transfer. The heat is transferred on the one hand from the heating line to the water in the water line and on the other via the contact point to the heat-conducting spray nozzle. The heating element is the same for both the spray nozzle and the water line and can be adapted easily to given structural conditions. The heating line requires no additional space and does not adversely affect the appearance. The heated water improves the cleaning action, so that the water consumption, and especially the especially the consumption of polluting additives, can be reduced. Finally, the installation is very simple, since an external plug connection on the nozzle is not needed, and the electrical contacting entails only slight costs, since the electric power supply is made only via a plug at the water supply.
To improve the heat transfer at the contact point, it is expedient to strip off the insulation of the current-carrying leads in the region of the contact point, so that the leads are bare where they rest on the spray nozzle of conductive material. The contact point can be embodied as a bore in the spray nozzle, into which the heating line is inserted. The ends of the leads can be retained by a conventional plug connection or soldered in place. An especially advantageous version is obtained if the spray nozzle is inserted in a nozzle body. In that case, the contact point can be formed by clamping, wedging and/or gluing the heating line in a joining gap between the nozzle body and spray nozzle. If the nozzle body is made from metal, an especially good heat transfer is obtained from the heating wire to the region of the spray nozzle. The nozzle body is expediently made from plastic. This provides thermal insulation from the outside, so that the heat output is concentrated in particular on the spray nozzle and the water. This leads to reduced energy consumption.
The joining gap is widened in the region of the contact point, to assure the sealing off from the outside. This sealing is typically achieved by means of a press fit between the spray nozzle and the nozzle body. It can be improved by means of a detent and sealing device that retains the spray nozzle in the nozzle body. Upon installation, the spray nozzle is clipped into the nozzle body, and at the same time the electrical and thermal contact with the heating line is made at the contact point.
Expediently, the spray nozzle has an outward-opening check valve, which prevents the water line from running empty if the windshield washer is not used for a long time. If the water line is only partly filled, the heat transfer to the water is impeded. Furthermore, water residues can become locally overheated and evaporate. This leads to calcium deposits, which over the course of time clog up the narrow channels in the spray nozzle.
The cleaning action can be improved by a plurality of spray nozzles that are disposed on the wiper arm, spaced a few centimeters apart from one another. To make installation easier, the nozzle bodies of the individual spray nozzles are integrally joined to one another and are connected to the water line. Furthermore, separate heating lines lead to the individual spray nozzles, to prevent all the water channels and spray nozzles from freezing shut at temperatures below the freezing point.